Home Networking Technologies

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Advances in communications technology to seamlessly connect all types of home
devices and appliances are driving the vision to create an intelligent home ecosystem.
This would enable control, access, and information sharing among all the devices and
thereby a much more enhanced user experience.
The future growth of electronics at home lies in the devices being able to wirelessly
communicate among themselves and with one or more universal handheld
portable multiradio devices (including other intelligent control points). Such a
control device would be able to control the other wireless-enabled devices in a distributed
or centralized manner. All devices would in the future come with some
type of a radio interface built into them. One could potentially conceive the giant
intelligent “home system” as being distributed but connected in a modular fashion
over a large-area wireless infrastructure. This naturally requires a vast amount of
research in various aspects of networking, from privacy/security to high performance
to seamless connectivity, emulating “being there” with the device or the equipment.

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Home Networking Technologies

  1. 1. TECHNOLOGIES FOR HOME NETWORKING Edited By SUDHIR DIXIT and RAMJEE PRASAD
  2. 2. TECHNOLOGIES FOR HOME NETWORKING
  3. 3. TECHNOLOGIES FOR HOME NETWORKING Edited By SUDHIR DIXIT and RAMJEE PRASAD
  4. 4. Copyright # 2008 by John Wiley & Sons, Inc. All rights reserved Published by John Wiley & Sons, Inc., Hoboken, New Jersey Published simultaneously in Canada No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400, fax 978-646- 8600, or on the web at www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, (201) 748-6011, fax (201) 748-6008. Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or comple- teness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The advice and strategies contained herein may not be suitable for your situation. You should consult with a professional where appropriate. Neither the publisher nor author shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages. For general information on our other products and services please contact our Customer Care Department within the U.S. at 877-762-2974, outside the U. S. at 317-572-3993 or fax 317-572-4002. Wiley also publishes it books in variety of electronic formats. Some content that appears in print, however, may not be available in electronic format. Wiley Bicentennial Logo: Richard J. Pacifico Library of Congress Cataloging-in-publication Data: Technologies for Home Networking edited by Sudhir Dixit & Ramjee Prasad. p. cm. Includes index. ISBN 978-0-470-07374-2 (cloth) 1. Home computer networks. 2. Home automation. I. Dixit, Sudhir. II. Prasad, Ramjee. TK5105.75.N48 2007 004.60 8—dc22 2007023223 Printed in the United States of America 10 9 87 65 432 1
  5. 5. To my brothers: Sushil, Sunil, and Sunit —Sudhir Dixit To my wife Jyoti, our daughter Neeli, our sons Anand and Rajeev, our granddaughters Sneha and Ruchika, and our grandson Akash —Ramjee Prasad
  6. 6. CONTENTS Preface xiii Contributor List xvii 1 Introduction to Networked Home 1 Mahbubul Alam, Sudhir Dixit, and Ramjee Prasad 1.1 Background, 2 1.2 Technology Adoption Trends, 6 1.3 Social Network, 8 1.3.1 Business Applications, 9 1.4 Consumer Trends, 9 1.5 Living in Real Time, 11 1.6 Confluence of Events, 11 1.7 Application and Service Convergence, 12 1.8 Network Convergence and Regulations, 14 1.9 Terminal Convergence, 15 1.10 Home Networking, 16 1.10.1 Home Computing, 17 1.10.2 Home Entertainment, 18 1.10.3 Home Communications, 18 1.10.4 Home Monitoring and Management, 19 1.11 Connected Home, 20 1.12 Vision of the Future, 21 1.13 Brief Overview of the Book, 22 1.14 Conclusions, 23 References, 25 vii
  7. 7. viii CONTENTS 2 Media Format Interoperability 27 Anthony Vetro 2.1 Background, 27 2.2 Media Formats, 29 2.2.1 Image and Video Formats, 29 2.2.2 Audio Formats, 30 2.2.3 Transport and File Formats, 32 2.2.4 Profiles and Levels, 33 2.3 Metadata Formats, 34 2.3.1 Content Descriptions, 34 2.3.1.1 Media Format, 35 2.3.1.2 Data Abstraction, 35 2.3.1.3 Multiple Variations, 36 2.3.1.4 Transcoding Hints, 36 2.3.2 Usage Environment Descriptions, 36 2.3.2.1 Terminal Capabilities, 37 2.3.2.2 Network Characteristics, 38 2.3.3 User Preferences, 38 2.3.4 Electronic Program Guide, 39 2.4 Media Adaptation, 39 2.5 Mandatory Media Format Profiles, 41 2.6 Media Format Interoperability: An Example, 42 2.7 Conclusions, 43 References, 44 3 Media Description and Distribution in Content Home Networks 47 Edwin A. Heredia 3.1 Diversification of Media Format Variants, 49 3.2 Content Home Network Architecture Components, 52 3.3 Content Format Variants in the Home, 55 3.4 Description of Content Features and Device Capabilities, 58 3.5 Media Exchange Description Language, 62 3.5.1 MXDL Media Object Descriptions, 63 3.5.2 MXDL Device Capability Descriptions, 66 3.6 Conclusions, 71 References, 72 4 Mobile Device Connectivity in Home Networks 73 Mika Saaranen and Dimitris Kalofonos 4.1 Related Work, 74
  8. 8. ix CONTENTS 4.2 Basic Home Use Cases, 75 4.3 Home Networking Challenges, 77 4.4 Architecture and Technologies for Local and Remote Home Connectivity, 80 4.4.1 Overview of Home Connectivity Architecture, 80 4.4.2 Local Connectivity, 81 4.4.3 Remote Connectivity, 85 4.5 Conclusions, 88 References, 89 5 Generic Access Network Toward Fixed – Mobile Convergence 93 Claus Lindholt Hansen 5.1 Trends in the Industry, 94 5.2 Standardization, 94 5.3 Gan Overview, 95 5.3.1 Security, 96 5.3.2 “Discovery” and “Registration”, 97 5.3.3 Rove in and Rove Out, 98 5.3.4 Transparent Access to Services in the Mobile Core Network, 98 5.3.5 GPRS Support in GAN, 98 5.3.6 Location Services, 98 5.3.7 Emergency Services, 98 5.3.8 GAN Protocol Architecture, 99 5.3.9 Bluetooth or Wi-Fi?, 100 5.4 Benefits with the GAN Technology, 100 5.4.1 Operators, 101 5.4.2 End User, 101 5.4.3 Terminal Availability, 102 5.5 Practical Experiences, 102 5.6 Impact on Networks and Processes, 102 5.7 Discussion, 103 5.8 Evolution of GAN, 104 5.9 Conclusions, 104 6 Secure Wireless Personal Networks: Home Extended to Anywhere 107 John Farserotu and Juha Saarnio 6.1 A Vision of a Personal Network, 109 6.2 Some Example Scenarios, 110 6.2.1 Health, 110
  9. 9. x CONTENTS 6.2.2 Home and Daily Life, 112 6.2.3 Distributed Work, 112 6.3 System and Requirements, 113 6.4 User Requirements and Scenarios, 115 6.5 Network Architecture, 115 6.6 Access and Access Control Techniques, 116 6.7 Security, 116 6.8 Devices and Service Platforms, 116 6.9 System Optimization and Operator Perspectives, 117 6.10 Toward Personal Services over Personal Networks, 118 6.11 Conclusions, 118 References, 119 7 Usable Security in Smart Homes 121 Saad Shakhshir and Dimitris Kalofonos 7.1 Survey of Related Work, 122 7.1.1 User Interaction with Security, 122 7.1.2 Security in Smart Spaces, 123 7.1.3 User Interaction with Security in Smart Spaces, 124 7.2 Basic Home Security Use Cases, 124 7.3 A Smart Home Security Model, 127 7.4 Design Challenges, 128 7.5 Usability, 129 7.6 Conclusions, 132 References, 132 8 Multimedia Content Protection Techniques in Consumer Networks 135 Heather Yu 8.1 Techniques for Multimedia Content Protection, 136 8.1.1 Basic Security Requirements for Content Protection, 136 8.1.1.1 Application Requirements, 136 8.1.1.2 Technology Requirements, 137 8.1.2 Traditional Techniques, 137 8.1.2.1 Encryption and Authentication, 137 8.1.2.2 Key Management, 137 8.1.2.3 Challenges for Multimedia Applications, 138 8.1.3 Advanced Cryptography Algorithms for Multimedia Content Protection, 139 8.1.4 Digital Watermarking, 139
  10. 10. xi CONTENTS 8.2 Techniques for Content Protection in Consumer Networking Environment, 141 8.2.1 Existing Consumer Entertainment Content Protection Technologies: A Quick Overview, 141 8.2.2 The Consumer Network “Boundary Problem”, 143 8.2.3 Case Study: Protecting Streaming Media in Heterogeneous Network Environment, 144 8.2.3.1 An Application Scenario, 144 8.2.3.2 Scalable Plaintext Media Streaming, 145 8.2.3.3 Scalable Secure Media Streaming, 145 8.2.4 Alternative Approach for Preserving Content Copyright Without Sacrificing Consumer Convenience and Freedom of Use, 146 8.3 Providing User-centric Services for Content Protection in Consumer Networks, 149 References, 150 9 Device and Service Discovery in Home Networks 153 Paul Wisner, Franklin Reynolds, Linda Kallstrom, ¨ ¨ Sanna Suoranta, Tommi Mikkonen, and Jussi Saarinen 9.1 Device and Service Discovery, 154 9.1.1 Common Attributes, 154 9.1.2 Interoperability, 155 9.1.3 Distributed Middleware Toolkits, 156 9.1.4 Other Discovery Protocols, 157 9.1.5 Directory Services and Other Configuration Management Systems, 157 9.2 The Home and the Extended Home, 158 9.2.1 Characteristics of the Home Environment, 158 9.2.2 Characteristics of the Extended Home Environment, 159 9.3 User Control Devices, 159 9.4 Selected Discovery Protocols, 162 9.4.1 SLP, 162 9.4.2 Bonjour, 164 9.4.3 Universal Plug and Play/SSDP, 165 9.4.4 Jini, 168 9.4.5 JXTA and JXTA Search, 169 9.4.6 DHCP, 171 9.4.7 Bluetooth SDP, 172 9.4.8 Web Services Dynamic Discovery, 174 9.4.9 eXtensible Service Discovery Framework, 175 9.5 Improving Service Discovery, 176 9.5.1 Security, 176
  11. 11. xii CONTENTS 9.5.2 Semantics and Automatic Composition, 177 9.5.3 Interoperability, 177 9.5.4 Touch, 177 9.5.5 Directories, 177 9.5.6 Location Awareness, 178 9.5.7 Service Browsing, 178 9.5.8 Proxies, 179 9.6 Conclusions, 179 References, 180 10 Small, Cheap Devices for Wireless Sensor Networks 183 Zach Shelby, John Farserotu, and John F.M. Gerrits 10.1 Impulse Radio UWB, 185 10.2 IEEE 802.15.4A, 188 10.3 Frequency Modulation UWB, 189 10.4 System-On-a-Chip, 193 10.5 Embedded Operating System, 194 10.6 Conclusions, 195 References, 195 11 “Spotting”: A Novel Application of Wireless Sensor Networks in the Home 197 Henry Tirri 11.1 Heterogeneous Wireless Sensor Network Architecture, 199 11.2 “Spotting”, 201 11.2.1 Tagging Physical Objects: “Spots”, 201 11.2.2 Spot Operations, 202 11.2.2.1 Spot Saving, 203 11.2.2.2 Spot Retrieval, 203 11.2.3 On Key Function K, 204 11.2.4 Spotting with Additional Sensor Information, 205 11.3 Conclusions, 205 References, 206 Index 207
  12. 12. PREFACE A person who is not disturbed by the incessant flow of desires—that enter like rivers into the ocean, which is ever being filled but is always still—can alone achieve peace, and not the man who strives to satisfy such desires. —The Bhagvad-Gita (2.70) The home networking market took off in about 2003, when consumers opted, in large numbers, for the high-speed Internet connection over DSL or cable connection. At about the same time, the prices of WLAN access points dropped to under $100, and a vast majority of households and enterprises began to deploy WLAN at their xiii
  13. 13. xiv PREFACE premises. Now, access points with much higher speed can be bought for under $50. Concurrent with the WLAN deployments, large-scale commercialization of Bluetooth, ZigBee, and other short-range radio technologies are under way to provide wireless interfaces to all types of devices and equipment at home and to inter- connect them in a seamless fashion. The In-Stat/MDR reports that by the year 2008, the home networking market will reach over $17 billion. Clearly, this market offers huge opportunities to the manufacturers and network providers and also to consumers to enjoy ultimate flexibility and significantly enhanced experience. In the future, it is anticipated that the private networks (e.g., home networks) would become part of the global network ecosystem, participating in sharing their own content and running IP- based services, (e.g., VoIP, IPTV), possibly becoming service providers themselves. This is already happening in the so-called social networks and peer-to-peer content delivery networks that are service-layer overlays on the Internet. Nevertheless, this trend has brought up the issues of digital rights and copyright management and secur- ity and authentication. This book is about the latest topics in home networking, such as the use cases, various networking technologies, security, service discovery, media formats and description, media distribution, security, digital rights management, and the role of sensor technologies in the home environment. Because each topic can easily expand into a book of its own and it is difficult to have in-depth knowledge in all of these domains, we chose to invite the various experts in the fields to contribute their thoughts. The book is written in a style to provide a broad overview of the home networking technologies with a special emphasis on the user as the center of all activities in the home. The book is aimed toward practicing engineers, graduate students, and researchers. It has been our objective to provide the material in one single place to enable quick learning of the fundamentals involved in an easy-to- read format. Finally, we (the authors and editors) have tried our best to ensure that each and every chapter is as accurate as possible; however, some errors in any manuscript are inevitable. Please let us know of any errors and ideas to improve the book— such comments will be highly appreciated. ACKNOWLEDGMENTS We are indebted to the contributors of this book for their hard work that made this book possible. All throughout this project, they were patient and forthcoming with any revisions we requested of them. Sudhir Dixit thanks his wife, Asha, daughter Sapna, and son Amar, for their support and understanding while he worked long hours editing this book. We express our gratitude to the staff of John Wiley, especially Paul Petralia and Whitney Lesch, for being patient with us as we missed deadlines several times to deliver the manuscript. They provided us invaluable help during the course of the whole publication process.
  14. 14. xv PREFACE We also thank the International Wireless Summit and the Wireless Personal Multimedia Conference, held in September 2005, where the chapters published in this book were first presented as the invited talks in a special session on home networking. SUDHIR DIXIT Mountain View, California RAMJEE PRASAD Aalborg, Denmark April 2007
  15. 15. CONTRIBUTOR LIST Mahbubul Alam, Cisco Systems (maalam@cisco.com) Sudhir Dixit, Nokia Siemens Networks, Mountain View, CA 94043, USA (sudhir.dixit@nsn.com) John Farserotu, CSEM ( john.farserotu@csem.ch) John F.M. Gerrits, CSEM (John.gerrits@csem.ch) Claus Lindholt Hansen, Ericsson (claus.1.hansen@ericsson) Edwin A. Heredia, Microsoft (eheredia@microsoft.com) ¨ ¨ Linda Kallstrom, Helsinki University of Technology (linda.kallstrom@tml.hut.fi) Dimitris Kalofonos, Nokia (dimitris.kalofonos@nokia.com) Tommi Mikkonen, Tampere University of Technology (tommi.mikkonen@tut.fi) Ramjee Prasad, Aalborg University, Aalborg, Denmark (prasad@es.aau.dk) Franklin Reynolds, Nokia (franklin.reynolds@nokia.com) Mika Saaranen, Nokia (mika.saaranen@nokia.com, mika.saaranen@ieee.org) Jussi Saarinen, Tampere University of Technology ( jussi.p.saarinen@tut.fi) Juha Saarnio, Nokia ( juha.saarnio@nokia.com) Saad Shakhshir, Nokia (shakhshir@gmail.com) Zach Shelby, University of Oulu (zach.shelby@ee.oulu.fi) xvii
  16. 16. xviii CONTRIBUTOR LIST Sanna Suoranta, Helsinki University of Technology (sos@tml.hut.fi) Henry Tirri, Nokia (henri.tirri@nokia.com) Anthony Vetro, Mitsubishi Electric Research Laboratories (avetro@merl.com) Paul Wisner, Nokia (paul.wisner@nokia.com) Heather Yu, Panasonic Research Laboratories (heathery@research.panasonic.com)
  17. 17. 1 INTRODUCTION TO NETWORKED HOME MAHBUBUL ALAM, SUDHIR DIXIT, RAMJEE PRASAD AND Advances in communications technology to seamlessly connect all types of home devices and appliances are driving the vision to create an intelligent home ecosystem. This would enable control, access, and information sharing among all the devices and thereby a much more enhanced user experience. The future growth of electronics at home lies in the devices being able to wire- lessly communicate among themselves and with one or more universal handheld portable multiradio devices (including other intelligent control points). Such a control device would be able to control the other wireless-enabled devices in a dis- tributed or centralized manner. All devices would in the future come with some type of a radio interface built into them. One could potentially conceive the giant intelligent “home system” as being distributed but connected in a modular fashion over a large-area wireless infrastructure. This naturally requires a vast amount of research in various aspects of networking, from privacy/security to high performance to seamless connectivity, emulating “being there” with the device or the equipment. Although there are currently handheld devices such as PDAs, PSPs, and iPODs, imagine one universal device (by which a person is still in control) with all of these features and more. Imagine this “wonder” device that can allow one to wire- lessly connect to (and control) one or more electronic devices within one’s house over an ad hoc network. Every new electronic device would come armed with an “antenna” to send and receive information and with some type of sensor built into it. The gizmo could be voice activated, touch screen activated, or be designed to take whatever input the user finds preferable and allow one to stay connected while roaming around the house, such as watching the television while moving Technologies for Home Networking. Edited by Sudhir Dixit and Ramjee Prasad Copyright # 2008 John Wiley & Sons, Inc. 1
  18. 18. 2 INTRODUCTION TO NETWORKED HOME FIGURE 1.1 A general depiction of devices interconnected with a home network. from room to room. This would also allow one to connect to one’s computer and play MP3 music that is not stored in it, or download a video stream, or stream a video to a server, or share it with someone else in a peer-to-peer configuration. One could acti- vate the coffeemaker from the bed, control the lights, watch the security video, control the thermostat, and so on and so forth. When the home network is connected to the Internet, it would also be possible to do all those things from a remote location as well either from a computer type of console or from the same handheld device as in the home. The home network of the future would be both under the control of the human and a machine that has been trained or has acquired knowledge from the user via self- learning techniques. In short, wireless connectivity would be the key enabler to creating smart space to enhance a person’s quality of life and to ease the use of the intelligent devices in his or her proximity. Figure 1.1 shows a general high- level depiction of what the future entails. Clearly, the opportunities are enormous. In this chapter, we first provide a broad overview of consumer, technology, and marketing trends to familiarize the reader with the drivers behind developing a net- worked home. This is followed by a brief outline of the rest of the book. 1.1 BACKGROUND Internet usage has approximately doubled since 2000, and in 2006, it stands at more than 1 billion people worldwide, or 18% of the world population. The rate of growth is slowing down but is expected to increase again once broadband is further
  19. 19. 3 1.1 BACKGROUND developed for high-speed, rich-media content delivered at a reduced price. Major growth in the future is expected from the developing countries with large populations. Much of the growth contribution will come from wireless and collaborative appli- cations that require access to the Internet. This has to be a wake-up call to pundits who have witnessed Internet access quickly becoming as ubiquitous as electric power, telephones, televisions, or any other public utility. It also does a lot to explain much of the current Internet hype that emphasizes non-PC applications. By applying a couple of simple rules of thumb, we can quickly ascertain where things are really headed and why. Figure 1.2 shows the mobile and broadband subscribers compared with the installed base of computers. At a very rudimentary level, there are two ways to grow the market adoption for any major new technology: 1. By attracting early adopters followed by normal consumers. 2. Through a generational change where nonusers literally die out to be replaced by a whole new generation of consumers who are comfortable with the new technology. Innovation can generally reach about two thirds of the market penetration through the first method, but to reach nearly 100% market share, the latter approach is required. That is the way it has always been even though people choose to forget that fact. That is why electricity and telephone, both of which have been with us for more than a FIGURE 1.2 Mobile and broadband subscribers versus installed base of laptops.
  20. 20. 4 INTRODUCTION TO NETWORKED HOME century, have almost 100% market penetration in most developed countries. People who are born today cannot imagine being without a telephone or electricity. The only communication product class to violate this intergenerational trend is broadcast television, which grew to above 90% market penetration in less than 30 years. That is most probably because television was perceived as an extension of radio by consu- mers and therefore maintained a much longer effective adoption cycle. Today, the Internet and cable television use in the United States are roughly com- parable at just under 70% market penetration. That means the commercial Internet, which effectively dates from the late 1980s, has grown at about three times the rate of cable TV, which began in the late 1940s and took until 1976 to reach 15% pen- etration. In fact, cable TV market penetration stood at 50% in 1987, about the time the commercial Internet came into being. Therefore, the Internet has grown a lot faster than these earlier communication technologies, but then the Internet is techni- cally dependent, for the most part, on some other host networks. At the very least, a consumer needs to be first a telephone or cable customer and then become an Internet customer. It seems obvious that whereas a generational shift will make Internet access almost universal in another 20 years, the same probably will not be said for cable TV, which may well peak and decline because there will be other ways to get television, for example, through mobile/cell phone (“mobile TV”), television on PC, laptops, PDAs, and so forth. That is the disruptive nature of the Internet, which threatens tele- phone companies, cable companies, and TV broadcasters alike. The result is that each of these industries is trying to enter the other’s market. As such, cable TV is the very heart of the U.S. broadband industry, even though broadband is what will probably end up eating into cable’s business. Telephone companies and Internet providers are also trying to find ways to enter the television business while VoIP is cutting into their voice business. While waiting for the intergenerational boom or bust, which is cyclical, each industry is building out to maximize the revenue from its exist- ing subscriber base. Cable TV companies do this by offering pay-per-view, digital cable, and video-on-demand. Telephone companies are starting to do the same. However, Internet companies have a slightly different task, and that is finding ways to connect more devices and more device types to their networks. That is because the Internet of today offers nothing more than the connection and the band- width. The value of the Internet is increased solely by the number of connections to it. In a nutshell, if the Internet industry is close to maxing out with connecting laptops, it is logical to start connecting non– PC-type devices (see Fig. 1.2). This is most prob- ably the number one reason and motivation for the start of the concept of connected home and home networking. Because in the past few years many TV shows and movies have suddenly been made available over the Internet, it has driven more types of devices to be connected to networks, which in turn will increase the business value of a network to its nominal owners. Figure 1.3 shows multiple devices connected to broadband. The real value here is to acknowledge that network unification is just a technical urge. The actual value achieved will drive all the existing networks into a single technology with wired and wireless varieties. This is a tectonic shift; it is slow but inevitable and
  21. 21. 5 1.1 BACKGROUND FIGURE 1.3 More devices are being connected to broadband. also irresistible. Of course, this vision of single technology is subject to national and local politics and short-term business advantages, but the trends are clear: † All networks will eventually be collapsed, converged, merged, or subsumed into the Internet. † Sharing the increased value of a single larger network will be worth more for information technology (IT) and information communication technology (ICT) companies than the incremental revenue from services running through different networks. Some of these cost savings could be passed onto the consu- mer, which will further fuel this trend. † The above trends will force a change in the network architecture. The client – server model has dominated the Internet for most of its existence, which is also the main cause of the scaling problem today. A question the reader may ask is how big the data center should be? before realizing that no data center is big enough for some applications, especially in the long run. In order to provide hundreds of millions of simultaneous unicast high-definition television (HDTV), data centers would need to be placed close to the consumer, which is certainly going to be very expensive. Surely, this is no way to make money. In other words, only server-to-server and peer-to-peer architectures make sense in the end. This is pretty much the only way the system can scale high enough to functionally improve and then replace today’s TV.
  22. 22. 6 INTRODUCTION TO NETWORKED HOME 1.2 TECHNOLOGY ADOPTION TRENDS What drove the entire semiconductor industry for the past 35 years was Moore’s law. Moore’s original statement can be found in his publication “Cramming more com- ponents onto integrated circuits” (Electronic Magazine, 19 April 1965): The complexity for minimum component costs has increased at a rate of roughly a factor of two per year . . . . Certainly over the short term this rate can be expected to continue, if not to increase. Over the longer term, the rate of increase is a bit more uncertain, although there is no reason to believe it will not remain nearly constant for at least 10 years. That means by 1975, the number of components per integrated circuit for minimum cost will be 65,000. I believe that such a large circuit can be built on a single wafer. Applying Moore’s law, as shown in Figure 1.4, to the networking and com- munication industries meant doubling the price-to-performance ratio every 18 months, which drove the IT industry. The same is expected to happen for the band- width-to-price ratio in networking, communication, and home networking industries. FIGURE 1.4 Growth of transistor counts for Intel processors (dots) and Moore’s law (upper line ¼ 18 months; lower line ¼ 24 months). Source: Wikipedia [1].
  23. 23. 7 1.2 TECHNOLOGY ADOPTION TRENDS High-definition entertainment, online gaming, and so forth, will load the networks according to Moore’s law and drive this industry for at least the next decade or two. During the early days of the Internet, universities were the first to embrace Internet services, such as e-mail and newsgroups. Financial industries and then general businesses were quick to follow in order to automate and improve their business pro- cesses, transactions, communications, and thereby reduce the overall operational costs. Service providers (SPs) were the last due to the slow deregulation of the tele- communications industry (unbundling of local loop), time to roll out massive network infrastructure, and high cost for bridging the last mile (see Fig. 1.5 for early adopters of Internet). These days, there is a paradigm shift in the adoption of innovative Internet services such as online gaming, social networks, file sharing, music/video sharing, and so forth. Universities are once again the early adopters of new services. Consumers then follow quickly, and then service providers offer those services and build their business model around those services. Finally, businesses adopt these services as they begin to understand the impact of these ser- vices on their business itself, and how these new trends, behavior, and expressions could be used as a vehicle for corporate messaging, marketing, product positioning, and attracting top talent. Thus, consumer electronics is driving the networking needs as never before, and this trend is only going to accelerate with the transport of all ser- vices and applications over the Internet Protocol (IP). As consumers demand faster broadband communications and entertainment ser- vices, demand for wired homes increases particularly at the higher end of the housing market. Real-estate developers are increasingly turning to optical technology with several fiber-to-the-home (FTTH) vendors working closely with master planned communities (MPCs). MPCs are residentially focused real-estate developments in which builders plan an entire community around shared services and amenities that attract buyers and renters alike. MPCs are leveraging more and more FTTH to provide premium services, which is mainly driven by the decline in the optical equip- ment costs. The benefit of FTTH is its bandwidth capacity, which is much more than needed for voice and data services. SPs could benefit from this increased bandwidth capacity by rolling out IPTV and IP video. FIGURE 1.5 Early adopters on Internet: past and present.
  24. 24. 8 INTRODUCTION TO NETWORKED HOME 1.3 SOCIAL NETWORK What is a social network? Is this a trend or a passing fad? What does it mean for communications, computer, consumer electronics, and media/content industries and how does it influence home networking? A social network is a human empow- ered network. A social network service is a platform specifically focused on the building and verifying of social networks for whatever purpose. Blended networking is an approach to social networking that combines both offline elements (face-to-face events) and online elements. Many social networking services are also blog-hosting services. As of 2005, there are more than 300 social networking Web sites. Social networking is a platform where people from all walks of life come together to express themselves by means of sharing videos, music, pictures, content, and so forth, and it provides the ability to collaborate using peer-to-peer applications and ser- vices. It provides a sense of virtually connecting people and platforms to share similar interests. This is a megatrend, and we have only witnessed the tip of the iceberg. The first social networking Web site was Classmates, which began in 1995. It was widely used in virtual communities. The popularity of these sites grew rapidly. By 2005, MySpace was getting more page views than Google. MySpace recently reported (mid-2006) that it has more than 100 million members and is adding half a million new users every week. Google recently bought $900 million worth of advertisement on MySpace. Bebo is one of the fastest growing social networks in the United Kingdom. Major telecommunications operators and businesses are just beginning to understand how these social networking services could have major societal impact on their service offerings, products, price, time-to market, and so forth. According to Reuters, YouTube is working to build a library of every music video ever created. Even media and label giants plan to work with YouTube on this project. Media/label/record companies are obviously interested in legitimate use cases, but they are more interested in finding out where this trend is going and how quickly they can adapt to it. Google Video also plays into this space. Major portal vendors like Microsoft launched Windows Live Spaces, which initially received a lot of atten- tion. The strong MSN brand and its broad product appeal marries Instant Message (IM), social networking, gadgets, blogging, and mashup under one umbrella. A blog is a user-generated Web site where entries are made in journal style and dis- placed in a reverse chronological order [2]. A mashup is a Web site or an application that combines content from more than one source into an integrated experience [3]. As of June 2006, Windows Live accounts for 30 million users, second only to MySpace. XuQa (the name is derived from “hookah”) is one of the me-too social networks focused on games such as poker with roughly 1 million users. It involves users par- ticipating in one big game. XuQa users play for peanuts by adding friends, uploading pictures, watching advertisements, and so forth. XuQa wants its users to sit through the advertisements and sign up for affiliated programs. Active users climb through 10 levels in the game for the ultimate prize of exposure on the XuQa home page and $1000 cash. AirG, a Vancouver-based mobile social network, is very promising. It is changing the way young people share and collaborate on content (e.g., AirG,
  25. 25. 9 1.4 CONSUMER TRENDS which hit the milestone of 10 million unique users, grew from 7 million users in just a few months). What makes mobile social networks like AirG so special? AirG has no PC-based network and works exclusively through a mobile phone interface unlike MySpace and Facebook, which both work with the PC and the handset. This indi- cates that mobility and the ability to do everything a PC can do while on the move at any time is not hype but soon to be the reality for the young generation. Flickr is a unique example of human networking. It is an online picture-sharing site where people can place comments and also critique them. People are now more than ever able to share their thoughts, comments, and ideas. Corporations are seeking these individual talents for their businesses and for their marketing cam- paigns. Social networks have opened doors to people from anywhere in the world to participate and expose their talents on a global basis. 1.3.1 Business Applications Social networks connect people with all different types of interests, and one area that is expanding in the use of these networks is the corporate environment. Businesses are beginning to use social networks as a means to connect employees and to help employees build profiles. This makes them searchable and connected with other business professionals. One example of a business social network is LinkedIn, a network that connects businesses by industry, functions, geography, and areas of interest. Networks are usually free for businesses or at a low cost; this is beneficial for entrepreneurs and small businesses looking to expand their contact base. These networks act as a customer relationship management tool for companies selling products and services. Companies can also use social networks for advertising in the form of banners and text advertisements. Because businesses are expanding glob- ally, social networks make it easier to keep in touch with other contacts around the world. 1.4 CONSUMER TRENDS The market in general is at an inflection point where enterprises and businesses are no longer in power but rather the end-users are (empowered human). Businesses harness the end-user energy to improve productivity. Some estimates claim that 40% to 50% of productivity can come from this kind of collaboration. Success in the consumer market and home networking is no different. It is not any more about technology but rather about emotional connection that people are going to make with brands and products. Take for an example Apple and iPOD. Consumers expect applications and services as shown in Figure 1.6, all in real time. For the con- sumer, it is about seamless delivery of applications, services, and entertainment anytime, anyplace, through any media player as shown in Figure 1.7. This implies convergence of applications, services, networks, and industries such as telecom, cellular, computing, media broadcasting, and so forth, with terminals.
  26. 26. 10 INTRODUCTION TO NETWORKED HOME FIGURE 1.6 Consumer expectation of applications and services all at real time. FIGURE 1.7 Many services to many screens.
  27. 27. 11 1.6 CONFLUENCE OF EVENTS 1.5 LIVING IN REAL TIME Doing things in real time over the net provides the real added value of the networked home, which is much more than simply accessing content stored locally in the home. Nowadays, everything resides somewhere on the network; living in real time means having access to network at all times and having some control capabilities for home monitoring, appliances, and other devices from remote locations. For it to become reality, convergence of information, commerce, and communications services is a must. Real-time information would include services such as news, education, search engine, health care, travel, TV, and so forth. Real-time commerce would mean online payment and online banking services. This will enable services such as online reservation and payment for movies, games, music, ring tones, entertain- ment, and ordering of goods and services. Communication services include tele- phone, video telephony, instant messaging, e-mail, multimedia services, and so forth. 1.6 CONFLUENCE OF EVENTS The mobile industry is huge with well over 2.3 billion subscribers and growing at more than 800 thousand subscribers per day. The majority of the growth is coming from the emerging economies with high populations, such as Brazil, Russia, India, China, Bangladesh, and so forth. With the increasing competition among fixed network oper- ators and mobile operators, the voice tariffs are under huge pressure to decline. In the meantime, explosion of broadband to home happened over the same period, and with more than 200 million connections worldwide and growing, free peer-to- peer Voice-over-IP (VoIP) and Session Initiation Protocol (SIP)-based voice services such as Skype became increasingly popular among residential users, teenagers, and students. Moving forward, VoIP is expected to take an increasing bite off the voice call market and will replace time- and distance-based charging with service-based flat tariff. Consequently, fixed telecom and cable operators have begun to expand their services offerings to triple play, namely, voice, video, and data (Internet connec- tivity) to combat declining voice revenue. During the same period, standardization of IEEE 802.11a/b/g standards and certification of Wi-Fi product granted vendor inter- operability, which resulted in increased market competition and drove price down for Wi-Fi chipsets and access points (APs). Soon, embedded wireless local area network (WLAN) chipsets became the mainstream feature just like infrared radio (IR) in laptops. Development of new service offerings, particularly multimedia applications and the notion of converged networks based on IP, have forced the equipment manufac- turers to consider multiple wireless connectivity solutions in products such as Bluetooth, Wi-Fi, IR, and so forth, in order to enhance consumer experience and meet their rising expectations. Figure 1.8 illustrates the confluence of events driving fixed-mobile convergence (FMC). Dual-mode phones and devices with Wi-Fi capabilities will leverage all these trends to connect to the mobile network and to Wi-Fi APs, which act as IP gateways between broadband IP-based fixed network and mobile networks. The device uses client software to provide soft switch- ing between mobile and fixed networks for continuity of voice call and for call handoff.
  28. 28. 12 INTRODUCTION TO NETWORKED HOME FIGURE 1.8 Fixed –mobile convergence is created by the confluence of events. For now, two approaches to client and gateway functionality have emerged, namely Unlicensed Mobile Access (UMA) and SIP. Ultimately, these approaches will con- verge into IP Multimedia Subsystem (IMS). 1.7 APPLICATION AND SERVICE CONVERGENCE Application convergence combines electronic subsystems that meld voice, data, and video into all sorts of electronic equipment, and with the availability of nanometer process technology, silicon IP vendors can use System-on-Chip (SoC) to develop, design, and build solutions. Application convergence means that different technol- ogies combine for one application such that various traffic types such as video, communication, and computing are in the same SoC design. Figure 1.9 depicts con- vergence of applications, services, and networks. An example is when computer- based applications like e-mail and customer relation management converge with communications applications like telephone calls and voice mail. The goal of service convergence is the fast delivery of voice, video, and data ser- vices with full mobility in an end-to-end secure architecture. Service mobility implies service continuity across network domains and devices. Wired, wireless, and mobile service providers are jockeying to own the customer. This will have an effect on the value chain for service delivery of entertainment, information, and communication. They understand that their ability to provide voice, video, and data capabilities for converged services will increase their customer loyalty, stickiness, and draw new
  29. 29. 13 1.7 APPLICATION AND SERVICE CONVERGENCE FIGURE 1.9 Convergence of applications, services, and networks. subscribers. Service convergence is not about quadruple play, which is voice, video, Internet, and mobility, but rather it is the ability to create new and innovative services based on the convergence of voice services, Internet services, and video services with mobility [4]. First, the architecture of these services will be loosely coupled where end devices will interwork to provide a converged service and later it will be a tightly coupled architecture where network and/or middleware will be intelligent to interwork with other services and peripheral networked devices to provide an even richer converged service user experience. FMC is a great example of service conver- gence. Another example of converged service is remote home monitoring and man- agement service (see Section 1.10.4). VoIP is currently being promoted as a replacement to traditional phone lines. Calls can be made on the Internet using a VoIP service provider and standard computer audio systems, a VoIP phone, or another similar multimedia device. Alternatively, some service providers support VoIP through ordinary telephones that use special adapters to connect to a home computer network. Converged messaging services such as Unified Communications (UC) services are expected to improve personal pro- ductivity and hence positively contribute toward the enhancement of human life. The first step of UC application will bring voice mail, e-mail, and faxes into a common inbox where they can be deleted, answered, forwarded, or saved. The next step for UC is integration of real-time presence application in order to reduce the number of unnecessary calls. It is not far when UC application will work with other wired and wireless peripheral networked devices to provide easier, faster, and better user
  30. 30. 14 INTRODUCTION TO NETWORKED HOME experience; for example, UC might include videoconferencing, file sharing, white board, a standard desktop/laptop and telephone feature, rather than something that needs to be specially scheduled. Just clicking on an icon brings additional partici- pants into the discussion with other home-networked devices. Service convergence will not only improve the home user experience. Service pro- viders are coming out with hosted solutions that harness UC technology to make contact centers more versatile than ever. These hosted solutions make it possible for contact centers to be onshore, near-shore, or offshore without heavy investment in infrastructure. As a result, the architecture of the center is highly flexible based on the needs and/or culture of the operation (i.e., they can be centralized, distributed, or home based). Using UC and the hosted application model, for instance, the call center can add home-based workers easily or ramp up existing operations at the drop of a hat. Thus, companies can extend their facilities across multiple time zones and locations and change their structure to fit seasonal loads. The real benefits of UC for businesses is physical virtualization of call center oper- ations that span continents via distributed contact centers and home-based agents. It may not make economic sense in certain geographical regions to set up full-fledged and dedicated contact centers to directly service the emerging middle class. However, the combination of UC and hosted call center solutions opens up new opportunities and new markets. Virtual contact centers can be deployed to service any language without the necessity of investing in infrastructure for each country. Some countries perhaps can have centers specific to their region, whereas others can cater to several languages using multilingual agents or via a network of home-based customer service representatives in the countries required. Another good reason for the marriage of UC and hosted solution is that in a global and virtual operation, it is desirable to have the same technology environment in every location. This makes it easier to manage glob- ally and to keep the costs down. Further, the customer gains a uniform experience no matter where they call in the world. 1.8 NETWORK CONVERGENCE AND REGULATIONS Mobile networks, fixed networks, and unbundled local loops all had a major impact on network convergence. Service providers competing to acquire new customers are faced with high subscriber churn rates, voice traffic moving from fixed to mobile net- works. For any given period of time, the number of participants who discontinue their use of a service divided by the average number of total participants is known as the churn rate. Churn rate provides insight into the growth or decline of the subscriber base as well as the average length of participation in the service. Furthermore, the rapidly declining voice tariffs are forcing the traditional network operators to reduce the total cost of ownership and operational expenditure by offering innovative services over a single IP-based network. Dual-mode phones are able to connect to mobile networks and Wi-Fi APs at home, public Wi-Fi hotspots, airports, hotels, work, and so forth, which are connected to an IP gateway between fixed and mobile networks. The purpose of this architecture is to enable an active call on
  31. 31. 15 1.9 TERMINAL CONVERGENCE any dual-mode phone to be switched (handover) back and forth between fixed broad- band and mobile networks depending on the best available network to reduce usage of licensed spectrum and to enable users to call using a single device at the lowest cost and to maintain the call connectivity. In many countries today, IP services such as VoIP, IPTV, and so forth, are treated as information rather than as telecommunication services. In some countries, national policymakers and regulatory authorities are revising licensing frameworks to make them more flexible and propose a generic or converged license for all forms of tele- communication services regardless of the underlying technology deployed or service offered. Some countries are exploring the possibility of decoupling the network oper- ations license from service provision, whereas other countries prefer a liberalized communication environment. 1.9 TERMINAL CONVERGENCE Development of new applications and services such as IP multimedia are forcing terminal manufacturers to consider including multiple wireless interfaces in products to provide even richer customer experience. Terminal vendors are challenged with the difficult task of balancing functionalities of devices with cost, power consumption, and the customer’s ergonomic expectations. This requires the terminal manufacturers to provide product differentiation in order to be competitive in the marketplace. This pressure will ultimately be passed on to silicon vendors for all converged devices and Convergence possibilities: new applications, new services, single terminal, FIGURE 1.10 and so forth.
  32. 32. 16 INTRODUCTION TO NETWORKED HOME terminals for home. A good example of this phenomenon is the mobile terminal market, which is subjected to most intense pressure and is all about unit volume ship- ments. With time, more and more radio technologies will find their way to smart devices, and handheld terminals will lead the way by implementing, for example, WiMAX (2.5 GHz) and ZigBee (2.4 GHz) for home automation applications. There already are six radios operating in 10 frequency bands within a single device such as GSM/GPRS/EDGE (850/900/1800/1900 MHz), WCDMA (1.9– 2.1 GHz), WLAN (2.4 GHz), GPS (1.5 GHz), Bluetooth (2.4 GHz), and FM Radio (88 – 108 MHz). Figure 1.10 illustrates concurrent seamless connectivity from the convergence of multiple radios and applications. 1.10 HOME NETWORKING Convergence of applications, services, and devices over IP-based networks is result- ing in a converged world leading to the evolutions of new business models. Network adaptability will be the key criteria to help meet the accelerating changes and make network responsive to the diversified needs and requirements. In addition, the businesses will need to be more agile than ever before. For business of the future to be agile, the questions that need to be answered are (1) Where should intelligence reside in order to deliver next-generation services—in net- works, in devices (software), in applications, or all of the above? (2) What will be the next-generation platform for service creation? Most likely, it will be the battle between different approaches and visions from different industry segments, such as network giant (Cisco), media player giants (Apple, Sony, Microsoft), mobile/ wireless networking and devices giants (Nokia, Ericsson, Motorola, Samsung), and applications/services giants (Google, Yahoo, Microsoft). These companies will push their architectural models for business acceptance, but ultimately, the platform of choice will be the one that will be open for businesses and developers to build their value-added services on. Home networking may be categorized under four main segments, namely, home computing, home network entertainment, home communications, and home monitor- ing and management, as shown in Figure 1.11. The core of home computing func- tionalities includes interworking between indoor (local area network) and outdoor (wide area network) networks and interconnecting multiple devices at home. Home network entertainment includes all networked consumer electronic devices such as X-Box, PS3, networked DVR, camcorder, TV, and so forth. Home communi- cation includes voice and video telephony, Wi-Fi phones, dual-mode phones, and so forth. Finally, home monitoring and management includes wireless remote control, remote surveillance and home systems management, and so forth. There is a major industrial initiative called Digital Living Networking Alliance (DLNA) to develop innovative new technology and to guarantee interoperability by leading consumer electronic, PC, and mobile handset companies, which allows users to easily acquire, store, and access digital content from almost anywhere in
  33. 33. 17 1.10 HOME NETWORKING FIGURE 1.11 Home networking segmented into personal computing, network entertain- ment, communications, and monitoring and management. the home. It enables users to effortlessly manage, view, print, and share their content. For example, on a DLNA home network, it is possible to access a home video from home digital video recorder and watch it on a PC anywhere in the home [5]. 1.10.1 Home Computing The basic requirements on home networking from the computing perspective are: † Interworking and distribution of high bandwidth to multiple devices in the home † Interworking between home IP gateway and wide area network (WAN) connection † Securing in-home communication and via WAN connection † Wireless enhancements for range and speed † Wired and wireless home network media † Distributed file sharing New higher speed access with freedom of movement in the home while maintain- ing security and privacy demands technologies that are capable of delivering secure high-speed quality and high-definition entertainment. Some of these are as follows: † Reliable wireless bandwidth over 100 Mbps (IEEE 802.11n). Higher bandwidth and longer-range wireless will enable home networks that can distribute high- bandwidth video content in and around the home.
  34. 34. 18 INTRODUCTION TO NETWORKED HOME † No new wires technologies such as † High-speed networking over existing coaxial cable (MoCA). † High-speed networking over existing telephone line (HomePNA). † High-speed networking over existing powerlines (HomePlug AV). HomePlug AV enables networked entertainment and Broadband over PowerLine (BPL) applications for home networking. HomePlug AV-based integrated circuit (IC) will allow consumers and service providers to distribute high-definition video and audio over existing in-home electrical wires, ushering in a whole new era of user-friendly entertainment connectivity. 1.10.2 Home Entertainment Entertainment on demand is on the march with the consumer. An example of a net- worked platform that offers consumer sticky application around digital media is con- sumer place-shifting device or software. Sling Media offers a consumer device that sits next to a residential digital set-top-box and allows a user to view his or her home-pay TV programs via Internet on a PC or on a mobile. On the other hand, Orb Networks’ solution is entirely software based, installed on PCs and mobiles. Orb announced a working relationship with Advanced Micro Devices (AMD), which might have important industry ramifications. Its technology will be the foundation for AMD’s Live media server capabilities and part of AMD’s Live entertainment PC platform. This will be the first time the PC industry puts ready-to-go in-built capabilities such as anytime, anywhere media streaming on PC into the hands of consumers, allowing them indoor and outdoor content delivery. Content storage for home is a fragmented market, and there is little demand for consumer-networked storage. Consumers store their files and digital media on their PC/laptop hard drives, external hard drives, USB drives, and/or burn CDs/DVDs. TV content is stored on DVRs and/or on PC with TV card. The home-networked content storage market is still underdeveloped but with consumer demand toward pro- ducing personal video content, sharing files, P2P video file transfer, IPTV, and so forth. Consumers are starting to see a large collection of their digital media files stored across multiple devices. This will generate demand for low-cost networked storage devices that can be accessed through various media players through different mediums (e.g., TV, PC, mobile phone, iPOD, MP3 player). 1.10.3 Home Communications Communication in-home involves the following: † Integrated communications for fixed and mobile: FMC is a great example for integrated fixed and mobile communications discussed earlier in this chapter. Another great initiative to promote FMC is the Fixed-Mobile Convergence Alliance (FMCA), which is a global alliance of telecom operators whose objective is to accelerate the development of convergence of products and services [6].
  35. 35. 19 1.10 HOME NETWORKING † Instant communications with federated user groups: User Personal Network (PN) device will enable a user to add and remove other users from his or her federation. Users belonging to a federation will be able to share all forms of communications instantly such as voice, video, IM, and so forth, with other users within the same federation. For more on the concept of PN-to-PN com- munications and PN-to-federation solutions, please refer to a worldwide R&D project called “My personal Adaptive Global NET (MAGNET)” [7]. † Presence integrated into voice communications: Voice communication systems integrated with real-time presence application will provide the users with the ability to see who else is logged-on to the network at the time and if the person on the other end of the communication link is willing to receive a call. This reduces the number of unnecessary calls and improves human interactions. This capability is currently available for corporate users, and it is expected to enter the residential market as VoIP begins to dominate the home communication market. To provide complete freedom of movement both to the user and home devices and to seamlessly connect them, wireless networking is emerging as the major new growth area of research and business opportunities. This would enable control, access, and information sharing among all the devices and much enhanced user experience. 1.10.4 Home Monitoring and Management There is growing importance of home monitoring and management. Recently, AT&T announced its new “AT&T Home Monitor” service, which allows subscribers to monitor their homes remotely, through a PC or AT&T (formerly Cingular Wireless) mobile phone. A key perceived benefit of this service is the ability to monitor activities of children and elderly parents remotely. With the ageing popu- lation, this service is poised to take off because it helps to reduce the cost of health care. In addition, it allows remote control of home lighting and potentially other networked appliances and receives a range of alerts and reports on conditions in the home, through a variety of motion detectors and temperature sensors. In monitoring and management, the following items have been characterized: † Remote surveillance † Home systems management † Heating, ventilation and air-conditioning (HVAC) and lighting control Service providers are motivated to offer this service because such services will help make their overall service offering attractive for subscribers. This will increase their subscriber stickiness and reduce the subscriber churn rate. Discontinuing the service would mean subscribers would lose their home monitoring service. Providers are also quite interested to offer these kinds of converged services due to the migration of appliances, sensors, and network architectures toward an all-IP – based technology.
  36. 36. 20 INTRODUCTION TO NETWORKED HOME 1.11 CONNECTED HOME In-home, there is an explosion of rich-media devices that can access different types of content blurring the lines between consumer electronics, computing technologies, and communication devices, delivering the same quality media to empowered consu- mers for in-home entertainment. Even though there is blurring of media devices, there are still many networks in- home that consumers have access to such as cable, DSL, satellite, fixed phone, IP phone over cable/DSL, FTTH, mobile phone, and so forth, as shown in Figure 1.12. Consumers demand simplicity—all they want is the availability and accessibility to services preferably over a single network. They do not care about which network does what, nor do they care which service provider provides what. Therefore, the service providers are in the process of reducing network operational cost by consolidating disparate networks into a single IP-based network so that a con- sumer only needs a single connection to his or her home. For consumers to have truly rich experience from a connected home, the following needs to happen: 1. Convergence of communication, computing technologies, and consumer electronics. 2. Delivery of rich media and content over a single network by service providers. FIGURE 1.12 Convergence of disruption will change the home networking architecture.
  37. 37. 21 1.12 VISION OF THE FUTURE FIGURE 1.13 (E)-/(re)-volution of digital home industry. 3. Seamless interworking and sharing of content between media devices and players. 4. Simplified user interface and preferably a single lightweight device for home networking control and management. Based on the topics discussed in this chapter such as technology adoption trends, consumer trends, and convergence of networks, applications, services, and terminals and from the section on home networking, we can derive an equation that will drive the future development of digital home industry: E / mc4 (1:1) where E is evolution of digital home industry, m is multimedia communications, and c 4 stands for content, consumer electronics, computer technology, and communi- cations technology. Figure 1.13 illustrates the clue to the (e)-/(re)-volution of digital home industry [8]. 1.12 VISION OF THE FUTURE Niels Bohr, the famous Danish physicist who made fundamental contributions to understanding of atomic structure and quantum mechanics, for which he received the Nobel Prize in 1922, said “Technology has advanced more in the last thirty years than in the previous two thousand. This exponential increase in advancement will only continue” [9].
  38. 38. 22 INTRODUCTION TO NETWORKED HOME Here we have what might be three new laws to guide future growth of the Internet, and they tell us a lot about what the future holds for us. 1. It is logical to assume that all devices will eventually be networked, but it will most probably start with devices that either are already intelligent (computers) or are very important to us (e.g., television, phone, and music system). Any political or business obstacles in the path of this transition are not likely to stay for long. 2. A possible way for the network to maximize its value is through server-to- server and peer-to-peer networking. Therefore, if ISPs do not want consumers to share or re-sell their Internet connection, it is just because they do not yet realize that such sharing is really to their advantage. In time, they will come to see it or they will slowly disappear. If ISPs do not like all that heavy traffic, it is just because they have not yet understood that in the long-term, they have to find ways to monetize the connections to be successful. 3. As we look into the future, the rate of change appears to be accelerating. Devices, systems, services, and applications capabilities are defined by soft- ware, which is changing much faster than hardware, mainly because the ser- vices today seem to last for a much shorter period than they used to when targeted toward the consumer market. Future generations will drive the demand for new and advanced information services. The future of home net- working will heavily revolve around this industry’s ability to improve the way we entertain, communicate, educate, and socialize in a secure way [10]. For the industry, this means that: 1. Market transitions will be customer driven. 2. Technology architecture with an economically viable business model will be required. 3. Networks and systems complexities must be hidden from the end-users. 1.13 BRIEF OVERVIEW OF THE BOOK This book on home networking has been organized to delve into the important enabling technologies to realize a home communications environment that improves the user’s experience, quality of life, and ease of use. This has meant covering other topics than only just those on networking. In addition to presenting the material in an easy to understand tutorial manner, the chapters also include the latest research results and technical advances on the various topics. To make all this happen, a holistic approach has been adopted to develop an intelligent wireless home ecosystem. A list of topics that are covered in this book is provided below. † Networked home use case scenarios † Media formats and interoperability
  39. 39. 23 1.14 CONCLUSIONS † Media description and distribution in content home networks † Mobile device connectivity in home networks † Generic access network toward fixed-mobile convergence † Secured personal wireless networks: home extended to anywhere † Usable security in smart homes † Multimedia content protection techniques in consumer networks † Device and service discovery in home networks † Small, cheap devices for wireless sensor networks † Spotting: a new application of wireless sensor networks in the home The book has been organized as follows. First, we have presented some back- ground and the key use case scenarios in this chapter to set the scope and give a perspective on the needed enabling technologies to realize an intelligent networked home. Because content distribution is one of the main functions performed by a home communication system, we therefore focus in Chapters 2 and 3 on the media descriptions, media formats, their interoperability, and distribution. In Chapter 4, we present how the mobile devices may be connected in the home network system, and what requirements do they impose on such a network both from the local connectivity and remote connectivity perspectives. Chapter 5 focuses on the Unlicensed Mobile Access (UMA) and Generic Access Network (GAN) protocols to enable fixed– mobile convergence in the home. In a virtual sense, the home network could be geographically distributed provided necessary security and authentication mechanisms have been built in. This is the topic of Chapter 6. As users become reliant on mobile devices to handle sensitive infor- mation in the home, requiring the home infrastructure to become increasingly wireless, there is an urgent need to provide credible solutions to security and privacy issues. This important topic is addressed in Chapter 7. A connected home will consist of multiple devices and services, which will require that they be sup- ported by some discovery mechanisms. This topic is covered in Chapter 8. Chapter 9 tackles the issue of digital rights management in the access and sharing of the multimedia content in consumer networks, such as in a home environment. It is anticipated that the home of the future will use all kinds of sensors for moni- toring, control, and data fusion. Chapters 10 and 11 delve into those issues and provide some innovative solutions and applications. One or more subject matter experts have addressed each topic in a detailed yet understandable manner. Because the authors have adequately addressed the issues, solutions, and the cross-layer functions, we feel it would be redundant to repeat them here. 1.14 CONCLUSIONS This chapter presented a broad view of consumer, technology, and industrial trends and interplay between them. It briefly described the phenomenon of living in real
  40. 40. 24 INTRODUCTION TO NETWORKED HOME time and the confluence of events. Further, it discussed the impact of social network- ing, convergence of services, applications, networks, and terminals. Finally, the development of the connected home and a vision for future was discussed. In summary, the key points are as follows. Moore’s law drove the semiconductor industry for the past 35 years, and applying this law to home networking and communications would mean doubling the bandwidth-to-price ratio every 18 months. As Niels Bohr, physicist Nobel Prize winner, said, “Technology has advanced more in the last thirty years than in the pre- vious two thousand. This exponential increase in advancement will only continue.” Home networking development will be driven by a new law E / mc 4, where E equates with evolution of digital home industry, m for multimedia communications and c 4 for content, consumer electronics, computer technology, and communications technology. Based on this new law for the digital consumer market, we can continue to expect major innovations in products and services for the years to come. Proliferation of IP-enabled devices and applications for home will continue for the near future. Focus is shifting from PC-centric devices and applications (with already high Internet penetration) to non – PC-centric devices and applications. These devices range from networked TV, networked DVR (IP-enabled set-top- box), online gaming, networked camera/camcorder, networked video surveillance, VoIP phones, dual-mode mobile phones, networked appliances, and various types of sensors. Place-shifting technology will revolutionize the consumer experience and expec- tations. It currently has the ability to deliver home TV content and manage home- networked DVR from any PC-centric device and mobile phones from any place, any where and any time. This technology is soon expected to enter mainstream PC and mobile entertainment platforms with support from chip manufacturers and service providers. Explosion of social networks, mashups, and blogs with online capabilities of photos and video sharing is a trend that is here to stay with us for a long time. Home networking appliance and device vendors will try to leverage this behavior and turn it into service and business benefits. IP-based fixed and mobile peer-to- peer services such as voice, video telephony, and gaming are poised to take off in a big way. This is a new trend, but globally there are still some hurdles and regulatory issues. Fixed Mobile Convergence (FMC) leading toward IP Multimedia Subsystems (IMS) is currently the best industry-wide, universally accepted architecture across fixed, mobile, and cable vendors and operators leading them toward triple, quadruple, and multiplay solutions. This is a major accelerator for IMS technology. The future of home networking will heavily revolve around industry’s ability to improve the way we entertain, communicate, educate, and socialize in a secure way keeping in mind that (a) market transitions will be customer driven, (b) solutions will be economically viable, and (c) network and system complexities must be hidden from the end-users because simplicity of the user interface is key to mass acceptance by consumers.
  41. 41. 25 REFERENCES REFERENCES 1. Moore’s Law. Available at http://en.wikipedia.org/wiki/Moore’s_law. 2. Blog. Available at http://en.wikipedia.org/wiki/Blog. /en.wikipedia.org/wiki/Mashup. 3. Mashup. Available at http:/ 4. Wireless Personal Communications. Special Issue, May 2006, Vol. 37, Nos. 3–4. /www.dlna.org/en/consumer/home. 5. Digital Living Network Alliance. Available at http:/ 6. Fixed-Mobile Convergence Alliance. Available at http://www.thefmca.com/. /www.ist-magnet. 7. My personal Adaptive Global NET (MAGNET). Available at http:/ org/. 8. S. Dixit and R. Prasad. Wireless IP and Building the Wireless Internet. Artech House, Norwood, MA, 2003. 9. Niels Bohr. Available at http://en.wikipedia.org/wiki/Niels_Bohr. 10. Mahbubul Alam et al., “Wireless Next Generation: 4G?,” pages 305– 316, In Multiaccess Mobility and Teletraffic for Wireless Communications, Vol. 5. Kluwer Academic Publishers, Norwell, MA, 2000.
  42. 42. 2 MEDIA FORMAT INTEROPERABILITY ANTHONY VETRO Digital media has become an integral part of our everyday lives, and consumers have access to content through a wide array of media services. This content may be transmitted over dedicated broadband networks, wireless networks, or the Internet, and it is received on a variety of different devices ranging from set-top boxes and television sets to portable media players, computers, and cell phones. While inter- operability does exist within specific application domains and media services, it is lacking among the broad range of diverse multimedia devices that could be found today. Part of the problem is that the content is compressed in a variety of different media formats making it difficult to transfer and consume content on different devices. This chapter introduces the media format interoperability problem in more detail by specifically discussing a subset of popular media formats and devices in use today. Several technologies that aim to solve the interoperability problem are then presented including the role of metadata formats and media adaptation technology. 2.1 BACKGROUND Content enters the home through a variety of ways. Broadcast services are provided through cable, satellite, and terrestrial transmission; Internet content is accessible through broadband connections via DSL or cable; and CDs and DVDs with the latest songs, movies, and television shows are available for purchase or rental. Standards provide a means for interoperability to be achieved, and within specific application domains and services, there are no serious interoperability problems that the consumer would need to be concerned with. For instance, the DVD you Technologies for Home Networking. Edited by Sudhir Dixit and Ramjee Prasad Copyright # 2008 John Wiley & Sons, Inc. 27
  43. 43. 28 MEDIA FORMAT INTEROPERABILITY just bought will not have any problem playing on your DVD player; the set-top box from your cable provider decodes and displays the compressed streams being sent to you through its service; and the song that you just downloaded from the Internet will play on your PC with the right software installed. However, with the growing demand for content portability (i.e., being able to experience content on any device), there is a distinct lack of interoperability. As the number of networks, types of devices, and content representation formats increase, interoperability between different systems and different networks is becoming more difficult. The aim is to provide a seamless interaction between content that is authored for one purpose and consumed in a different way. Figure 2.1 attempts to illustrate this problem. On one side, we have a variety of content sources and on the other we have a set of connected devices in the home. The media formats and network i nterfaces between these devices are not uniform, thereby making connectivity and media portability a challenging task. The rest of this chapter is organized as follows. In the next section, the various media formats that exist today will be covered, including audiovisual compression formats as well as some common transport and file formats. In the following two sec- tions, related technologies that help bridge the gap between the different media formats, and networks that they are connected to, are discussed. The first related tech- nology is metadata, which is useful for describing not only the content itself but also the distribution and consumption environment as well. In dynamic and heterogeneous networking environments, an essential first step is to understand the mismatch and steps that need to be taken to achieve interoperability. The second related technology is media adaptation, which is the process to convert the media from its source format into a format that could be consumed on a target device. In an effort to minimize the adaptations required in a home network, an approach that defines sets of mandatory FIGURE 2.1 Illustration of several content sources including broadcast, Internet, and CD/DVD, as well as connectivity in the home among a diverse set of media devices.
  44. 44. 29 2.2 MEDIA FORMATS media formats for a defined set of devices classes is also discussed. We then conclude the chapter with an example of media format interoperability and provide a summary of the topics covered. 2.2 MEDIA FORMATS This section provides an overview of some common image, video, audio, and system layer formats that are supported in home network devices and discusses key appli- cations domains for each format. We also present the concept of profiles and levels, which define interoperable conformance points for specific coding formats. 2.2.1 Image and Video Formats Image and video coding play an important role in bridging the gap between large amounts of visual data and limited bandwidth networks for video distribution. During the past two decades, a number of image and video coding standards have been developed to satisfy industry needs. These standards have been developed by two major standards organizations: International Organization for Standardization/ International Electrotechnical Commission (ISO/IEC) and the International Telecommunication Union (ITU). The Joint Photographic Experts Group (JPEG) has produced well-known stan- dards such as JPEG [1] and JPEG 2000 [2]. A key difference between the two stan- dards is that JPEG is based on the Discrete Cosine Transform (DCT), whereas JPEG 2000 is based on the Discrete Wavelet Transform (DWT). JPEG 2000 also supports higher compression efficiency, scalability, and a variety of other features such as error-resilience. JPEG is a ubiquitous image format on the Web and also the primary format used in digital cameras today, and JPEG 2000 is beginning to find applications in video surveillance and digital cinema. In addition to these standar- dized formats, there exist a host of other popular image formats, such as Graphics Interchange Format (GIF) (which utilizes a variation of run-length coding known as Lempel – Ziv –Welch coding), Portable Network Graphics (PNG), Tagged Image File Format (TIFF), and so on. On the video side, the Moving Picture Experts Group (MPEG) of ISO/IEC and the Video Coding Experts Group (VCEG) study group of ITU-T have also produced a series of successful video coding standards, many of which have been jointly devel- oped. H.261 was completed in 1990 by the ITU-T and is mainly used for Integrated Services Digital Network (ISDN) video conferencing [3]. MPEG-1 was completed in 1992 under ISO/IEC with the target application being digital storage media on CD- ROM, at bit rates up to 1.5 Mbit/s [4]. MPEG-2, which is also referred to as H.262, was completed in 1994 by both ISO/IEC and ITU-T [5]. This standard is an exten- sion of MPEG-1 and allows for greater input format flexibility and higher data rates for both high-definition television (HDTV) and standard-definition television (SDTV). MPEG-2 is used as the video format in most digital television (DTV) systems around the world and is also the format used for DVD. H.263 was completed in 1996 by the ITU-T and was largely based on the H.261 framework [6], and
  45. 45. 30 MEDIA FORMAT INTEROPERABILITY TABLE 2.1 Summary of Select Image and Video Coding Formats Name Major Features JPEG DCT-based still-image coding format used for Web pages and digital cameras. JPEG-2000 DWT-based still-image coding format with improved coding efficiency. Used for surveillance and digital cinema applications. H.261 Video coding format developed primarily for video conferencing applications with bit-rates in the range of 64 kbit/s to 1.92 Mbit/s. MPEG-1 Video coding up to 1.5 Mbit/s. Target application was video storage on CD-ROM but also widely used on the Internet. MPEG-2 Extension of MPEG-1 coding for higher quality applications such (H.262) as DTV/DVD. Support for higher bit-rates and input picture resolutions. Most extensively used video coding format. H.263 Designed for very low bit-rate coding, below 64 kbit/s. MPEG-4 Includes tools to support content-based coding and low bit-rates Part 2 coding. Used for mobile video and streaming applications. H.264/AVC Significant improvements in coding efficiency over MPEG-2 and (MPEG-4 MPEG-4 Part 2. Wide application for DTV and HD-DVD. Part 10) VC-1 Coding performance close to H.264/AVC and also targets a wide number of DTV/DVD applications. MPEG-4 Part 2 was completed in 2000 by ISO/IEC [7] and is compatible with H.263. The Simple Profile and Advanced Simple Profile of MPEG-4 Part 2 have been used for mobile application and streaming. Finally, the most recent video coding standard, H.264/AVC, which is also referred to as MPEG-4 Part 10, was developed by the Joint Video Team (JVT) of ISO/MPEG and ITU-T/VCEG [8]. H.264 greatly improves the coding performance over MPEG-2 and MPEG-4 Part 2 by achieving the same quality at approximately half the bit-rate. The target appli- cations include broadcast television, high-definition DVD, and digital storage. A summary of the image and video coding formats is shown in Table 2.1. Currently, the most popular video coding standards include MPEG-2, MPEG-4 Part 2 (Simple Profile and Advanced Simple Profile), and H.264/AVC (Baseline Profile). It should be noted that besides the video coding standards developed by MPEG and VCEG, there are also video coding schemes such as VC-1 (informal name of the SMPTE 421M video codec standard) developed by Microsoft and stan- dardized by the Society of Motion Picture and Television Engineers (SMPTE) [9], as well as RealVideo, which is a proprietary format developed by RealNetworks. Such media formats are extensively used for video streaming over the Internet. In the case of VC-1, it has also been adopted into the specifications developed by the BluRay Disc and HD-DVD Forums. 2.2.2 Audio Formats Audio coding has been central to the deployment of a wide variety of services including television and radio broadcast, as well as music distribution via CD or over the Internet.
  46. 46. 31 2.2 MEDIA FORMATS The most popular coding formats for streaming audio on the Internet today include MP3, a standardized coding format developed by MPEG, as well as the proprietary Windows Media Audio (WMA) and RealAudio formats, which have been developed by Microsoft and RealNetworks, respectively. For high-quality applications, such as music CD, television broadcast, and DVD, the uncompressed Linear Pulse Code Modulation (LPCM) format, as well as Advanced Audio Coding (AAC) and AC-3 (also known as Dolby Digital) compression formats, have been more prevalent. A summary of select audio coding formats is shown in Table 2.2. LPCM is an uncompressed audio format [10]. With up to 8 channels of audio at 48-kHz or 96-kHz sampling frequency and 16, 20, or 24 bits per sample, the maximum bit-rate could go up to 6.144 Mbyte/s. However, the format encoded on most CDs and DVDs use 48-kHz sampling and 16 bits per sample. MP3 is a perceptual audio encoder that encodes the audio signal based on the characteristics of the human perception of sound [11]. In such as scheme, the parts of the audio signal that humans perceive distinctly are coded with high accuracy, and the less distinctive parts are coded less accurately. Typical MP3 bit-rates are in the range of 8 kbit/s to 320 kbit/s. The sampling frequencies defined by MPEG-1 include 32 kHz, 44.1 kHz, and 48 kHz. MP3 also works on both mono and stereo audio signals. MPEG-2 AAC is a more efficient and flexible encoding scheme and is able to achieve perceptually transparent quality at only 64 kbit/s per channel [12]. Sampling rates range from 8 kHz up to 96 kHz and above, and bit-rates may go as high as 256 kbit/s. The standard also supports up to 48 channels, as well mono, stereo, and all common multichannel configurations such as 5.1 or 7.1. MPEG-2 AAC has been adopted by both the European and Japanese digital television broad- casting systems. TABLE 2.2 Summary of Select Audio Coding Formats Name Major Features LPCM An uncompressed audio format used in CD and DVD. Typical sampling rate of 48 kHz and 16 bits per sample. MPEG-1 (MP3) Perceptual audio encoder with bit-rate in the range of 8 to 320 kbit/s. Popular audio format on the Web and in portable music players. MPEG-2 (AAC-LC) Perceptually transparent quality at only 64 kbit/s per channel. Support for up to 48 channels and bit-rates up to 256 kbit/s. Adopted for European and Japanese broadcast. MPEG-4 (HE-AAC) Improved coding efficiency. Good quality stereo at 16 to 24 kbit/s. Used for satellite radio and adopted by 3GPP. AC-3 (Dolby Digital) First coding format specifically designed for multichannel sound. Adopted for use in U.S. terrestrial broadcast, satellite television, DVD. WMA Popular format for Internet-based streaming applications. Also supported in consumer electronics devices.
  47. 47. 32 MEDIA FORMAT INTEROPERABILITY MPEG-4 HE-AAC, which stands for high-efficiency AAC and is also referred to as aacPlus, improves coding efficiency with the use of a bandwidth expansion tool referred to as Spectral Band Replication (SBR) [13]. With this coding tool, it is poss- ible to achieve good stereo quality at bit rates of 32 to 48 kbit/s. In the second version of this standard, parametric stereo coding tools are also added, which reduces the required bit-rates to around 16 to 24 kbit/s for stereo content. These coding tech- niques have been adopted by 3GPP for mobile music services and for satellite radio providers such as XM Radio. There are a variety of additional flavors of AAC that target low-delay, scalability, and lossless compression. Further details may be found in Ref. 14. AC-3 is also a perceptual digital audio coding technique. AC-3 was the first coding system designed specifically for multichannel digital audio, but it also supports mono and stereo coding as well. Because an early target of this audio coding format was television broadcast in the United States, the specification of AC-3 is defined by the Advanced Television Systems Committee (ATSC) [15]. AC-3 supports sampling rates of 32, 44.1, and 48 kHz with bit-rates in the range of 64 to 640 kbit/s. Besides being adopted for terrestrial digital television broadcast in the United States, AC-3 is also widely used for satellite television systems, DVD, and gaming. WMA and RealAudio are proprietary formats that are mostly found on the Web for streaming applications. However, with the desire to network consumer electronic devices with PC and to play-back music recorded from the PC on CD/DVD players, these formats are also supported on wide variety of devices in the home. 2.2.3 Transport and File Formats As discussed in previous sections, the audiovideo coding formats convert the digital media to compressed formats that are represented as binary streams. The main task of the transport and file formats is focused on multiplexing and synchronizing of these coded media streams into a single bitstream or multiple bitstreams. To perform these tasks, mechanisms are needed to distinguish the different media and also to provide timing and synchronization capabilities. In this section, we cover three such formats from the MPEG-2 and MPEG-4 standards, which hopefully will highlight different requirements and keys aspects of existing system-level formats. The MPEG-2 Systems standard, also referred to as H.222, specifies two formats: the Transport Stream (TS) and the Program Stream (PS) [16]. Each is optimized for a different set of applications, which are discussed further below. An important feature of any system-level stream is being able to retrieve the coded media from within the transport stream, decode it, and present the decoded results. To achieve this, the system-level stream is first demultiplexed, and relevant data including both system- and media-related data would then be decoded and presented in a synchronized manner. The TS is a system-level stream definition that is designed for communicating or storing one or more programs of coded video, audio, or other kind of data in lossy or noisy environments in which significant errors may occur. The TS is able to combine one or more programs with one or more time bases into a single stream. This is the
  48. 48. 33 2.2 MEDIA FORMATS typical system-level format used for broadcasting services around the world, including cable, satellite, and terrestrial transmission. The program stream on the other hand is defined for the multiplexing of audio, video, and other data into a single stream for communication or storage applications. The essential difference between the program stream and transport stream is that the transport stream is designed for applications in which some level of noise must be tolerated, such as in over-the-air broadcasting, whereas the program stream is designed primarily for applications that enjoy a relatively error-free environment, such as in DVD and other digital storage applications. As such, the overhead in the program stream is less than in the transport stream. The MP4 file format that is part of the MPEG-4 specification [17] offers a versatile container to store content in a form that is suitable for streaming. The MP4 file format can be used to store multiple variations of the same content and to select an appro- priate version for delivery. The hint track mechanism supported by the MP4 file format allows supporting multiple transport formats [e.g., Real Time Transport Protocol (RTP) and MPEG-2 TS] with minimal storage overhead. Another unique characteristic of the MP4 file format is that the audiovisual media data is stored sep- arately from its metadata, which includes timing information, the number of bytes for a video frame, file location, and so on. Also, in contrast with previous standards, the timing information is not absolute, but relative; this feature helps facilitate editing operations. 2.2.4 Profiles and Levels Profiles and levels are critical concepts regarding media format interoperability. Profiles essentially limit the set of tools that need to be implemented from a decoder’s point of view. Levels on the other hand define the complexity bounds. The profile and level combination provides a well-defined conformance point, which is needed to ensure interoperability between different implementations and to also enable testing for conformance to the standard. It should be noted that profiles and levels exist for all types of media coding formats, including video, audio, graphics, and system layers. It is noted that profiles in the context of MPEG and other bodies that define coding standards are specified for a particular coding format. Combinations of audio and video formats are not typically defined by such standards bodies; this has traditionally been done by various industry forums. For instance, ATSC specified the use of MPEG-2 Systems, MPEG-2 Video, and AC-3 Audio for digital terrestrial broadcast- ing in the United States [18]. Considering the latest H.264/AVC standard, several profiles targeting different classes of applications have been defined. Each of these profiles allows a certain set of coding tools to be used for video compression. For instance, the Baseline profile only allows I- and P-slices, while the Main profile additionally allows B-slices. As another example, error-resilience tools are quite useful for applications that transmit data over noisy channels but might not necessarily be required for all applications. Therefore, such tools would be included in only a subset of profiles.

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